First example shows automatic correction of lateral chromatic aberration. When correct lens profile was used, older versions of LR did a pretty good job with lateral CA, too.

Another example of one click correction of lateral chromatic aberration correction. Further improvement would be possible with the local removal tool.

This picture was taken with Zeiss Distagon 28ZE. The lens shows strong purple fringing more often than other lenses. This one was significantly reduced by a single click in LR. In this case, the eyedropper did not work well, but the automatic correction did good enough job.

Extreme case of CA – again, Zeiss Distagon 28/2. First picture is 100% crop from 21MP uncorrected. The second is the same crop after correction (with eyedropper used to select the fringe color). The purple areas were desaturated, but the result is much more acceptable than the original . The third shot shows the whole picture and the desaturated areas are not visible. The crop if from top left corner.

Now an example of longitudinal (axial) chromatic aberration. This example is from Zeiss Makro-Planar 100 ZE.

Before correction:

After correction:

See excellent explanation and examples of chromatic aberrations on http://toothwalker.org/optics/chromatic.html

View from the Window at Le Gras (1826)

Few years after making this picture Niépce teamed up with Daguerre to bring the quality to whole new level. But this photograph has started it all.

Niépce was born in France on March 7, 1765, 246 years ago. On March 7 2011, Digital Photo Calculator for iPhone will be available at substantial discount.

Happy anniversary!

Weight and size considerations

70-200/4 is small and light and 70-200/2.8 is big and heavy. The difference was very obvious during the side by side tests. 70-200/2.8 IS II is used by professionals everywhere, but if you consider switching from 70-200/4 to 70-200/2.8 for light travel with lots of hiking or walking all day around cities, make sure you try the lens first.

Image stabilizer

The IS seems to be equally effective on both lenses. The f/2.8 lens has quieter implementation – no clunking sounds when it disengages.

Color and contrast (200mm)

The f/2.8 lens makes a bit darker pictures, which makes it difficult to compare such things as contrast and color. But the f/2.8 lens seems to be more vibrant on equal apertures.

Full frame (almost – some distracting foreground features were cropped out), click to enlarge.

100% crop from 21MP, default LR settings.

Sharpness at 200mm – handheld with IS on

So far tested on 30 ft or greater distances only. The 70-200/2.8 seems marginally sharper. 100% crops from 21MP, default capture sharpening in LR (click to enlarge).

Sharpness near minimal focusing distance (70mm and 200mm)

The following two images show sharpness at MFD at 70 and 200mm, both shot wide open, that means, f/2.8 on one lens and f/4 on the other.

Sharpness at 100mm

70-200/2.8 IS II vs. 70-200/4 IS at f:4 and f:8

All shots tripod mounted. Distance of the DVD sleeve is about 10ft/3m.

EF70-200mm f-4L IS USM at f/4 IS on

EF70-200mm f-4L IS USM at f/4 IS off

EF70-200mm f-4L IS USM at f/8 IS off

EF70-200mm f-2.8L IS II USM at f/4 (IS off)

EF70-200mm f-2.8L IS II USM at f/8 (IS off)

70-200/2.8 IS II compared to Zeiss 100/2 Makro-Planar at f:2.8

All shots tripod mounted. Distance of the DVD sleeve is about 10ft/3m.

Makro-Planar at f:2.8, actual pixels from 21MP

The zoom at 100mm and f:2.8, tripod mounted with IS on

The zoom at 100mm and f:2.8, tripod mounted with IS off

Focusing speed and accuracy

Tested on EOS 5D2, the focusing speed of both lenses is about equal, but the AF feels smoother on the f/2.8 lens.  While the f/4 sometimes needed 2 (fast) attempts, the f/2.8 needed only one.

To be continued.

Interactive comparison of both lenses on The Digital Picture

User reviews on Fred Miranda

Review of 70-200/2.8 IS II on DPReview

Review of 70-200/2.8 IS II on Diglloyd (requires subscription)

Depth of field  (DOF) is impacted by the following factors:

Using equivalent focal length lens

Compared to full frame (FF), crop format cameras have smaller sensors and smaller field of view. Therefore, photographers who use such cameras generally use shorter lenses to achieve the same field of view compared to “reference” full frame camera. Equivalent focal length can be calculated by multiplying actual focal length by crop factor. For example, Nikon APS cameras have crop factor 1.5.  50mm lens mounted on Nikon APS will have equivalent field of view of 50 x 1.5 = 75mm lens on FF. And conversely, 50mm lens mounted on FF camera will have equivalent focal length 50/1.5 = 33mm.

Shorter lenses have greater depth of field, so if a photographer uses equivalent focal length lens on a crop camera, achieved depth of field will be deeper than on full frame. Focal length is the key, but not the only factor here. If we compare prints from a FF camera and a crop camera of equal size, the crop camera print, coming from smaller chip, will be enlarged more.  In that Nikon example, we have to enlarge 1.5x compared to FF. More enlarged edges and details will look less sharp and will give perception of shallower depth of field.

The following chart takes the different levels of enlargement into account and depicts hyperfocal distance in meters at different f-stops (1.4 – 22) for 50mm lens on FF and equivalent focal lengths on crop cameras.

Parameters:

The above chart shows that even if we consider the greater enlargement needed for crop factor, using equivalent focal length lens on crop camera will provide more depth of field than FF. That means that FF can achieve shallower depth of field than cameras with smaller sensors. It also means that if FF photographer and crop photographer shoot scene from the same distance and maintain the same subject size in their viewfinder and use the same f-stop, the crop photographer will have greater DOF in his shot.

But does it also mean that with crop factor we can achieve greater depth of field?

Factoring in diffraction limit

If great depth of field is our goal, we stop down the lens. We should not stop it down beyond diffraction limit though.  The following chart shows hyperfocal distance for various crop factors at diffraction limited (largest sensible) f-stop for each format (for all sensors at 13MP). The chart is for 50mm for FF and equivalent lenses for crop factors > 1.

Parameters: same as above.

It appears that if we take 50mm lens of FF camera and stop it down to f/13, or equivalent FL lens on a crop factor and stop it down to their diffraction limit, the achieved maximum depth of field is about the same. Minor differences between crop factor bars in the chart are apparently caused by rounding error.

Using the same lens

If using the same lens, in order to achieve the same subject size, photographer with crop camera must step further away compared to photographer with FF camera. Depth of field increases with distance, so even though the lens and f-stop are the same, the DOF will be larger with crop camera.

The following chart shows depth of field in meters for FF and crop camera. The distance on x axis is for shooter with FF camera, crop shooter is further away to achieve the same field of view.

Parameters:

• Open the App Store app
• Go to the Featured tab
• Navigation bar on the top should now show New button
• Scroll down and there should be an item called Redeem
• Enter the promotion number there. The download should start automatically

Are you writing iOS app reviews and looking for promotion codes? My apps are featured here. If you are interested in writing a review and need a free download code, contact me.

Find suitable print

Find a print that has reasonably large patches of maximum density. I like to use print test target from Uwe Steinmueller.

Measure the darkest patch with ColorMunki Photo

ColorMunki Photo ships with Photo ColorPicker application.

• Use ColorPicker to measure your darkest patch.
• Repeat the measurement several times
• Find the darkest measured patch. This will be the patch that has smallest L value

Once you measured the patches and found the darkest, you can use Digital Photo Calculator iPhone App to convert the value to Dmax.

There is also an online calculator on Bruce Lindbloom’s web site that can convert Lab values to density.

Some practical examples

• Find maximum resolution achievable with your camera. If you know your sensor type (APS, FF etc.) and resolution in MP, you can calculate resolution in lp/mm
• Find diffraction limit of your sensor. If you know your sensor size and resolution, you can calculate what is the maximum f-stop you can use before diffraction starts deteriorating the image
• See visual representation of RGB and Lab color
• Convert between RGB and Lab or RGB and RGB
• Find Dmax and Dmin with ColorMunki or another spectrophotometer. If your calibrator/spectrophotometer returns Lab readings of your prints, you can use Digital Photo Calculator to calculate Dmax and Dmin values (or any other density). Just get reading of darkest/lightest areas of your print in Lab and enter the numbers to Digital Photo Calculator
• See visual differences between RGB numbers in different color spaces. Enter RGB values and preview the color while switching between sRGB, AdobeRGB and ProPhoto RGB
• Find web color for given Lab or RGB value. Digital Photo Calculator can convert Lab, sRGB, AdobeRGB and ProPhoto RGB to web color representation (#RRGGBB)
• Find 35mm equivalent focal length. Select your sensor size and focal length and the app will calculate what focal length on a FF camera would have the same field of view

Check out the links below to see all available functions.

More info

More detailed information, screenshots and Q&A are available on http://www.elsners.org/apps/dpcalc/.

Adobe Labs released Lens Profile Creator utility that enables creation of custom lens profiles for Photoshop CS5 (ACR 6.1) and Lightroom 3.

This page contains profiles for some Zeiss ZE lenses for Canon EOS 5D II that I created using that tool. The profiles are free to use.

Currently there are profiles for the following lenses:

• Distagon 21mm ZE
• Distagon 28mm ZE
• Makro-Planar 50mm ZE
• Makro-Planar 100mm ZE

Click here to download

Update 4/16/2011

Profile for Zeiss Distagon 35/1.4 is now available for download:

Click here to download Distagon 35/1.4 profile

Update 5/24/2011

Profile for Summicron 28/2 Asph:

Click here to download Summicron-M 28/2 Asph profile

Examples

Chromatic aberration

Extreme corner shot with Distagon 28/2, uncorrected.

Extreme corner shot with Distagon 28/2, corrected with ACR 6.1

Distortion and vignetting

Distagon 21mm, uncorrected (click the image for larger picture)

Distagon 21mm, corrected in ACR 6.1. Exact same settings, but lens correction on.

Distagon 21 – distortion correction

Update Aug 22, 2010

Locations for the profile files

For Windows Vista or Windows 7

C:\Users\(User Name)\AppData\Roaming\Adobe\CameraRaw\LensProfiles\1.0
C:\ProgramData\Adobe\CameraRaw\LensProfiles\1.0

For Mac

/Users/(User Name)/Library/Application Support/Adobe/CameraRaw/LensProfiles/1.0
/Library/Application Support/Adobe/CameraRaw/LensProfiles/1.0

Update:

Adobe Camera Raw 6.2 and Lightroom 3.2 now ship with profiles for Zeiss Z* lenses.

Digital Unsharp Mask

Unsharp mask selectively increases contrast of edges and small objects by making dark areas of edges darker and light areas of edges lighter. Since this creates a sharpening effect, unsharp mask is frequently used to improve apparent sharpness in digital imaging. The following image shows enlarged detail of an edge with and without unsharp mask. The image consists of two gray boxes; the upper part is with USM applied.

If USM is used with narrower radius settings, it can effectively increase apparent sharpness. The following image shows effect of the unsharp mask on an image. The first character R is normal, the second is a copy of the first one with gaussian blur applied and the third one is a copy of the blurred one with unsharp mask applied.

If USM is used with wider radius settings, it can increase micro contrast.

Eberhard Effect

Exposed molecules of silver halides react during development with developing agent and convert the white silver halide into black silver and creates visible photographic image. This chemical reaction breaks up the developing agent and creates certain byproducts that are capable of retarding further chemical reaction – development. Eberhard found that if developer is left absolutely still, smaller details and edges are developed more rapidly than larger areas, because smaller areas and edges can be easily surrounded by fresh developer, while silver halide particles inside large areas are surrounded by exhausted developer that does not have the vigor of the fresh one. Eberhard effect can be observed in still developers and diluted developers, but exists in conventional development as well and is frequently used by photographers to increase micro contrast and apparent sharpness. The effect can be replicated by digital unsharp mask. An extreme detail boosting technique, which turns photograph into graphics is based on copying or enlarging the photographic image to a large format high contrast film and developing with emulsion soaked in developer pressed on a glass sheet so that there is only thin layer of developer that can’t move. The film is copied and developed this way several times. I applied USM  on black and white image in Photoshop four times to achieve visually identical effect:

As you can see, tonality is gone and the image is created only by local contrast.

Micro Contrast in Lenses

Camera lenses also exhibit micro contrast – or lack thereof. Lenses with good micro contrast  have good MTF at frequencies around 10lp/mm. There is some consensus that Zeiss lenses consistently excel in micro contrast.

The following two images are taken at the same day and hour, identically processed, but with two different lenses. First was taken with Canon EF 35/1.4L and second with Zeiss Distagon 28/2 ZE. Both are sharp lenses, but one has bad micro contrast and one has good. Click on the images to see larger version.

Useful links:

http://www.luminous-landscape.com/tutorials/understanding-series/lens-contrast.shtml

http://www.zeiss.com/C12567A8003B8B6F/EmbedTitelIntern/CLN_30_MTF_en/$File/CLN_MTF_Kurven_EN.pdf

General Thoughts

How I Work

I’m using full frame camera and the suitability of lenses described below is related to full frame cameras only. I never use flash and rely on fast lenses and high ISO performance of my camera.

Age

The requirements and usability of lenses change with the ability of the baby to move. When they start walking, the AF speed becomes more important, especially during the age when they can’t understand everything you say and any attempt to stop them or attract their attention only causes that they start running to you. This has been a challenge especially with my 85mm lens and to some extent with 50mm.

Focal Length

Most of my photographs are from indoors, a situation which usually calls for shorter fast lenses. For baby photography I have been using mostly 85mm, 50mm and 35mm focal lengths, in that particular order.

EF 17-40/4L

Suitable for snapshots where it is necessary to get very close or where you need to include lots of background. The minimum aperture of 4 is limiting for indoors shots, but ok during daylight. You will often get close enough for the child to be able to reach the front element of the lens. Since the lens hood is shallow and won’t prevent the baby from actually reaching the glass, an UV filter is handy. If you are considering purchasing a wide angle zoom lens and plan to use it for baby photography, think about 16-35/2.8 II, which is more practical for low light situations.

EF 35/1.4L

This 35mm lens is considered by some the best wide angle lens from Canon, some reviewers rate it higher than 35mm Summilux R from Leica, but I found achieving sharp looking shots more complicated than with other lenses. Wide open it has shallow depth of field, but does not isolate the main subject the same way as longer fast lenses. This may create tricky situations on pictures with multiple isolated subjects, where some of the photographed subjects are not perfectly sharp and the viewer percepts this as bad focus. This may and may not be a problem for your type of photography. This lens can be hand hold at 1/30s and at wide open allows taking pictures with virtually no light. This is great especially during the period when baby works in 3 hours cycle and lots of interesting photo opportunities (feeding) happen in the middle of the night.

EF 50/1.4

I found this lens practical especially in the hospital. It is relatively unobtrusive, light and universal enough to cover all the needs. This lens is fast, makes nice background blur and I would recommend this lens for baby photography to anyone on budget.

EF 85/1.2L II

This is my most used lens. 85/1.2 closest focusing distance works great for adult portraits, but babies are smaller and you won’t be able to get close enough to fill the frame with head and shoulders of several months old baby. When they grow and start to move, this lens’ AF system is not fast enough to track their movement. Nevertheless, the fast aperture and background blur made it my favorite baby lens. The 85/1.8 is faster and focuses from closer distance and should be a great alternative.

EF 135/2L

Greater shooting distance makes this focal length great for shooting unnoticed. Also great for details with blurred background. This lens is sharp wide open and despite the longer focal length can be used indoors. It’s sharpness and beautiful background blur make it tempting to use it wide open, but babies, especially those that can walk, may easily move after locking the focus and before the exposure and easily get out of the shallow depth of field. Using AI-servo, checking the shots for sharpness,multiple exposures and stopping down the lens will help mitigate the problem.

Other lenses

The only other lens from my collection that I used for baby photography was 180/3.5 macro. I used it for some detail shots but also for shots where the 135mm was short. This is a great lens and the pictures are fine, but as one would expect, this lens is absolutely impractical for macro shots of moving subjects. Shorter macro lens would serve that purpose much better.

Useful Links

http://www.fredmiranda.com/reviews/index.php?cat=45

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx

http://www.16-9.net/lens_tests

Update – Two Years Old

At two years, ability to track the child and quickly frame became more important than anything else.

EF 16-35/2.8 II

This lens proves to be very practical for action shots. It allows taking reasonable pictures even if the kids get very close to you – and this happens a lot, especially if you talk to them. It also allows reasonable framing without cropping in post processing when the kid or kids quickly move back and forth.

EF 35/1.4L

Still one of the favorite lenses for that purpose, especially in low light, like these pictures taken when my daughter befriended with our waitress in a restaurant and the other one from a hotel room.

EF 85/1.2L

Great for portraits. While lenses like the 16-35 allow the photographer to become part of the action, the 85 gives you certain distance and isolation allowing you to capture totally different moments.